Cord tightening device



FIG. 1 is a top view showing my new design for a cord tightening device,

FIG. 2 is a left side view thereof;

FIG. 3 is a front view thereof;

FIG. 4 is a front perspective view thereof;

FIG. 5 is a bottom view thereof;

FIG. 6 is a right side view thereof; and,

FIG. 7 is a rear view thereof. 

The ornamental design for a cord tightening device, as shown and described. 